1. Field of the Invention
The present invention relates to a process for producing a highly chlorinated copper phthalocyanine by a chlorination of a copper phthalocyanine, particularly, it relates to an industrial advantageous process for producing a highly chlorinated copper phthalocyanine by a chlorination of a copper phthalocyanine.
2. Description of the Prior Art
A copper phthalocyanine is a blue pigment. A green pigment is obtained by chlorinating a copper phthalocyanine to substitute 12 or more of hydrogen atoms of benzene rings with chlorine atoms preferably to substitute with 13 or more of chlorine atoms among 16 of sites. A brilliant yellowish green pigment is obtained by substituting with 14 or more of chlorine atoms.
The highly chlorinated copper phthalocyanine pigment is called as copper phthalocyanine green or phthalocyanine green and it is a pigment having excellent light fastness and solvent resistance.
In the well-known industrial process for producing a highly chlorinated copper phthalocyanine by a chlorination of a copper phthalocyanine, a copper phthalocyanine is dissolved in a molten mixture of anhydrous aluminum chloride and sodium chloride and it is contacted with chlorine gas at 160.degree. to 200.degree. C. to chlorinate the copper phthalocyanine and the reaction mixture is poured into a large amount of ice water and the chlorinated copper phthalocyanine is separated.
This process is widely carried out as an industrial process since a brilliant yellowish green pigment can be easily obtained. However, the following disadvantages are found.
(1) A cost for a recovery of aluminum chloride and sodium chloride is too high to carry out as an industrial purpose and a cost for treating aluminum chloride in a waste water is remarkably high because 5 to 8 times by weight of anhydrous aluminum chloride to a copper phthalocyanine is used and the reaction mixture is poured in water.
(2) A chlorination is carried out at high temperature of 160.degree. to 200.degree. C. whereby various by-products are formed to decrease a yield.
On the other hand, it has been known to produce a highly chlorinated copper phthalocyanine by dissolving a copper phthalocyanine in chlorosulfonic acid and charging chlorine into the solution in the presence of a catalyst in U.S. Pat. No. 2,662,085.
This process has advantages.
(1) A reaction temperature is upto 115.degree. C. and an operation is easier and a corrosion of an apparatus is lower in comparison with those of the aluminum chloride-sodium chloride process.
(2) A cost of chlorosulfonic acid is lower than that of anhydrous aluminum chloride.
However, this process has not been carried out as an industrial process because of the following reason.
(1) An yield is remarkably lower than that of the aluminum chloride-sodium chloride process.
(2) A hue of the resulting pigment is not good and bluish and a brilliant yellowish green has not been given.
It has been also known to produce a highly chlorinated copper phthalocyanine by chlorinating a copper phthalocyanine in a solvent of pyrosulfuryl chloride with thionyl chloride in Japanese Pat. No. 15790/1962.
This process is not an industrial process because a large amount of thionyl chloride is used.
The inventors have studied to provide a process for producing a highly chlorinated copper phthalocyanine which is to overcome the disadvantages in the conventional processes. In Japanese Patent Application No. 148081/1977 (Japanese Unexamined Patent Publication No. 81334/1979), it has been proposed to provide a process for producing a highly chlorinated copper phthalocyanine having brilliant yellowish green in high yield and industrial advantages in a solvent of chlorosulfonic acid or pyrosulfuryl chloride under reducing disadvantages caused in the conventional processes using such solvent. However, in the former process, a large amount of inorganic strong acidic compounds such as sulfur oxyacid chlorides have been used as a solvent whereby various industrial disadvantages such as corrosion of the apparatus are caused in the separation and recovery of a residue containing the object product by distilling and recovering the solvent components from the reaction mixture.
On the other hand, it has been also known to chlorinate a copper phthalocyanine by feeding chlorine gas at a temperature higher than 150.degree. C. in the presence of a suitable catalyst such as aluminum chloride, zinc chloride, cupric chloride, antimony trisulfide, iodine and sulfur chloride in an organic solvent which is inert to chlorine such as carbon tetrachloride, trichloroacetic acid, nitrobenzene, trichlorobenzene, tetrachloroethane, chloroindane and phthalochloride as the solvent for reaction. In any cases, the chlorination is not enough at a reaction temperature of lower than 150.degree. C., and yellowish green product could not be obtained but only bluish green product is obtained. For example, at a reaction temperature of 120.degree. C., only 12 of hydrogen atoms among 16 of hydrogen atoms on the benzene rings of the copper phthalocyanine are substituted by chlorine atoms.